People who developed persistent apathy and depression for the first time months after having COVID-19 have roughly 18% fewer nerve terminals that use dopamine than healthy people, according to Canadian researchers cited by ScienceAlert.
Dopamine is a neurotransmitter that helps control movement and motivation. The loss of nerve terminals that carry dopamine signals affects cognitive function and can contribute to neurodegenerative diseases, according to the report.
The research team analyzed PET brain scans of 24 adults with long COVID and 24 healthy people of roughly the same age. Specialists measured the loss of dopamine nerve terminals in the striatum, a central brain region responsible for movement and motivation.
How the scans worked
Participants were given a radiotracer that binds to a protein found in nerve cells that transmit dopamine signals, called the vesicular monoamine transporter 2, or VMAT2. VMAT2 is a biomarker used in research into neurodegenerative diseases such as Parkinson's disease, according to the report.
What the scans revealed
The PET scans showed that loss of dopamine nerve terminals in the ventral striatum was linked to decreased motivation. In the dorsal striatum, loss of terminals in the putamen was associated with slowed movements and longer times to complete tasks.
Loss in the caudate nucleus was linked to decreased memory and difficulty recalling words. Damage to dopamine nerve terminals was found even in people who had lived with long COVID for up to 4.6 years, the researchers reported.
Cigarette smoking has separately been linked to a higher risk of long COVID, with smokers more often experiencing the condition's main symptoms, according to the report.
